package com.YHVision.qiuzhike.service.impl;

import cn.hutool.core.collection.CollUtil;
import com.YHVision.qiuzhike.exception.BusinessException;
import com.YHVision.qiuzhike.model.entity.Question;
import com.YHVision.qiuzhike.model.entity.QuestionBank;
import com.YHVision.qiuzhike.service.QuestionBankService;
import com.YHVision.qiuzhike.service.QuestionService;
import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.YHVision.qiuzhike.common.ErrorCode;
import com.YHVision.qiuzhike.constant.CommonConstant;
import com.YHVision.qiuzhike.exception.ThrowUtils;
import com.YHVision.qiuzhike.mapper.QuestionBankQuestionMapper;
import com.YHVision.qiuzhike.model.dto.questionBankQuestion.QuestionBankQuestionQueryRequest;
import com.YHVision.qiuzhike.model.entity.QuestionBankQuestion;
import com.YHVision.qiuzhike.model.entity.User;
import com.YHVision.qiuzhike.model.vo.QuestionBankQuestionVO;
import com.YHVision.qiuzhike.model.vo.UserVO;
import com.YHVision.qiuzhike.service.QuestionBankQuestionService;
import com.YHVision.qiuzhike.service.UserService;
import com.YHVision.qiuzhike.utils.SqlUtils;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.ObjectUtils;
import org.springframework.aop.framework.AopContext;
import org.springframework.dao.DataAccessException;
import org.springframework.dao.DataIntegrityViolationException;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.stream.Collectors;


/**
 * 题库题目服务实现
 *
 * @author <a href="">YHVision-小y</a>
 * @from <a href="todo">爱编程学习圈</a>
 */
@Service
@Slf4j
public class QuestionBankQuestionServiceImpl extends ServiceImpl<QuestionBankQuestionMapper, QuestionBankQuestion> implements QuestionBankQuestionService {

    @Resource
    private UserService userService;

    @Resource
    private QuestionBankService questionBankService;

    @Resource
    private QuestionService questionService;

    /**
     * 校验数据
     *
     * @param questionBankQuestion
     * @param add      对创建的数据进行校验
     */
    @Override
    public void validQuestionBankQuestion(QuestionBankQuestion questionBankQuestion, boolean add) {
        ThrowUtils.throwIf(questionBankQuestion == null, ErrorCode.PARAMS_ERROR);
        //不需要校验
//        // todo 从对象中取值
//        String title = questionBankQuestion.getTitle();
//        // 创建数据时，参数不能为空
//        if (add) {
//            // todo 补充校验规则
//            ThrowUtils.throwIf(StringUtils.isBlank(title), ErrorCode.PARAMS_ERROR);
//        }
//        // 修改数据时，有参数则校验
//        // todo 补充校验规则
//        if (StringUtils.isNotBlank(title)) {
//            ThrowUtils.throwIf(title.length() > 80, ErrorCode.PARAMS_ERROR, "标题过长");
//        }
    }

    /**
     * 获取查询条件
     *
     * @param questionBankQuestionQueryRequest
     * @return
     */
    @Override
    public QueryWrapper<QuestionBankQuestion> getQueryWrapper(QuestionBankQuestionQueryRequest questionBankQuestionQueryRequest) {
        QueryWrapper<QuestionBankQuestion> queryWrapper = new QueryWrapper<>();
        if (questionBankQuestionQueryRequest == null) {
            return queryWrapper;
        }
        // todo 从对象中取值
        Long id = questionBankQuestionQueryRequest.getId();
        Long notId = questionBankQuestionQueryRequest.getNotId();
        Long questionBankId = questionBankQuestionQueryRequest.getQuestionBankId();
        Long questionId = questionBankQuestionQueryRequest.getQuestionId();
        String sortField = questionBankQuestionQueryRequest.getSortField();
        String sortOrder = questionBankQuestionQueryRequest.getSortOrder();
        Long userId = questionBankQuestionQueryRequest.getUserId();
        // todo 补充需要的查询条件
        // 精确查询
        queryWrapper.ne(ObjectUtils.isNotEmpty(notId), "id", notId);
        queryWrapper.eq(ObjectUtils.isNotEmpty(id), "id", id);
        queryWrapper.eq(ObjectUtils.isNotEmpty(userId), "userId", userId);
        queryWrapper.eq(ObjectUtils.isNotEmpty(questionBankId), "questionBankId", questionBankId);
        queryWrapper.eq(ObjectUtils.isNotEmpty(questionId), "questionId", questionId);
        // 排序规则
        queryWrapper.orderBy(SqlUtils.validSortField(sortField),
                sortOrder.equals(CommonConstant.SORT_ORDER_ASC),
                sortField);
        return queryWrapper;
    }

    /**
     * 获取题库题目封装
     *
     * @param questionBankQuestion
     * @param request
     * @return
     */
    @Override
    public QuestionBankQuestionVO getQuestionBankQuestionVO(QuestionBankQuestion questionBankQuestion, HttpServletRequest request) {
        // 对象转封装类
        QuestionBankQuestionVO questionBankQuestionVO = QuestionBankQuestionVO.objToVo(questionBankQuestion);

        // todo 可以根据需要为封装对象补充值，不需要的内容可以删除
        // region 可选
        // 1. 关联查询用户信息
        Long userId = questionBankQuestion.getUserId();
        User user = null;
        if (userId != null && userId > 0) {
            user = userService.getById(userId);
        }
        UserVO userVO = userService.getUserVO(user);
        questionBankQuestionVO.setUser(userVO);
        // endregion

        return questionBankQuestionVO;
    }

    /**
     * 分页获取题库题目封装
     *
     * @param questionBankQuestionPage
     * @param request
     * @return
     */
    @Override
    public Page<QuestionBankQuestionVO> getQuestionBankQuestionVOPage(Page<QuestionBankQuestion> questionBankQuestionPage, HttpServletRequest request) {
        List<QuestionBankQuestion> questionBankQuestionList = questionBankQuestionPage.getRecords();
        Page<QuestionBankQuestionVO> questionBankQuestionVOPage = new Page<>(questionBankQuestionPage.getCurrent(), questionBankQuestionPage.getSize(), questionBankQuestionPage.getTotal());
        if (CollUtil.isEmpty(questionBankQuestionList)) {
            return questionBankQuestionVOPage;
        }
        // 对象列表 => 封装对象列表
        List<QuestionBankQuestionVO> questionBankQuestionVOList = questionBankQuestionList.stream().map(questionBankQuestion -> {
            return QuestionBankQuestionVO.objToVo(questionBankQuestion);
        }).collect(Collectors.toList());

        // todo 可以根据需要为封装对象补充值，不需要的内容可以删除
        // region 可选
        // 1. 关联查询用户信息
        Set<Long> userIdSet = questionBankQuestionList.stream().map(QuestionBankQuestion::getUserId).collect(Collectors.toSet());
        Map<Long, List<User>> userIdUserListMap = userService.listByIds(userIdSet).stream()
                .collect(Collectors.groupingBy(User::getId));
        // 填充信息
        questionBankQuestionVOList.forEach(questionBankQuestionVO -> {
            Long userId = questionBankQuestionVO.getUserId();
            User user = null;
            if (userIdUserListMap.containsKey(userId)) {
                user = userIdUserListMap.get(userId).get(0);
            }
            questionBankQuestionVO.setUser(userService.getUserVO(user));
        });
        // endregion

        questionBankQuestionVOPage.setRecords(questionBankQuestionVOList);
        return questionBankQuestionVOPage;
    }

    /**
     * 批量添加题目到题库
     * @param questionIdList
     * @param questionBankId
     */
    @Override
    public void BatchAddQuestionsToQuestionBank(List<Long> questionIdList, long questionBankId, User loginUser) {
        //数据校验
        ThrowUtils.throwIf(CollUtil.isEmpty(questionIdList), ErrorCode.PARAMS_ERROR, "题目id列表不能为空");
        ThrowUtils.throwIf(questionBankId <= 0, ErrorCode.PARAMS_ERROR, "题库id不能为空");
        ThrowUtils.throwIf(loginUser == null, ErrorCode.NOT_LOGIN_ERROR);
        //根据题库id获取题库信息
        QuestionBank questionBank = questionBankService.getById(questionBankId);
        ThrowUtils.throwIf(questionBank == null, ErrorCode.NOT_FOUND_ERROR, "题库不存在");
        //根据题目id获取题目信息
        //List<Question> questionList = questionService.listByIds(questionIdList);查询其实使用的是select *，数据库查询避免使用
        //查询优化，避免查询使用select *，影响性能(SQL优化)
        LambdaQueryWrapper<Question> questionLambdaQueryWrapper = Wrappers.lambdaQuery(Question.class)
                .select(Question::getId)
                .in(Question::getId, questionIdList);
        //得到的合法的题目列表返回值类型是Long，但这里得到的是一个Question对象类型，比较占用内存，优化：转换成Long类型
        //合法的题目列表(优化后)
        List<Long> validQuestionIdList = questionService.listObjs(questionLambdaQueryWrapper,obj -> (Long) obj);
        ThrowUtils.throwIf(CollUtil.isEmpty(validQuestionIdList), ErrorCode.NOT_FOUND_ERROR, "题目列表不存在");
        //合法的题目列表(优化前)
//        List<Long> validQuestionIdList = questionList.stream()
//                .map(Question::getId)
//                .collect(Collectors.toList());
//        ThrowUtils.throwIf(CollUtil.isEmpty(questionList), ErrorCode.NOT_FOUND_ERROR, "题目列表不存在");
        //判断题目是否在题库中
        LambdaQueryWrapper<QuestionBankQuestion> lambdaQueryWrapper = Wrappers.lambdaQuery(QuestionBankQuestion.class)
                .ne(QuestionBankQuestion::getQuestionBankId, questionBankId)
                .in(QuestionBankQuestion::getQuestionId, validQuestionIdList);
        List<QuestionBankQuestion> existQuestionList = this.list(lambdaQueryWrapper);
        //将不存在题库中的题目添加到需要添加到题库中的题目列表中去
         Set<Long> existQuestionIdSet = existQuestionList.stream()
                .map(QuestionBankQuestion::getId)
                .collect(Collectors.toSet());
         //过滤掉已经存在于题库中的题目id
        validQuestionIdList = validQuestionIdList.stream().filter(questionId ->{
                return !existQuestionIdSet.contains(questionId);
        }).collect(Collectors.toList());
        ThrowUtils.throwIf(CollUtil.isNotEmpty(validQuestionIdList), ErrorCode.NOT_FOUND_ERROR, "题目已存在题库中");

        // 自定义线程池,IO密集型
        ThreadPoolExecutor customExecutor = new ThreadPoolExecutor(
                20,                          // 核心线程数
                            50,                        // 最大线程数
                            60L,                       // 线程空闲存活时间
                            TimeUnit.SECONDS,          // 存活时间单位
                            new LinkedBlockingQueue<>(1000),  // 阻塞队列容量
                            new ThreadPoolExecutor.CallerRunsPolicy() // 拒绝策略：由调用线程处理任务
        );

        //保存所有批次的任务
        List<CompletableFuture<Void>> futures = new ArrayList<>();

        //批量添加题目到题库
        //分批添加到题库，避免长事务问题，每批 1000 题
        int batchSize = 1;
        int totalbatchSize = validQuestionIdList.size();
        for (int i = 0; i < totalbatchSize; i += batchSize) {
            List<Long> batchQuestionIdList = validQuestionIdList.subList(i, Math.min(i + batchSize, totalbatchSize));
            //todo 添加重试机制，防止由于网络不稳定造成偶发失败
            List<QuestionBankQuestion> questionBankQuestions = batchQuestionIdList.stream()
                    .map(questionId -> {
                        QuestionBankQuestion questionBankQuestion = new QuestionBankQuestion();
                        questionBankQuestion.setQuestionBankId(questionBankId);
                        questionBankQuestion.setQuestionId(questionId);
                        questionBankQuestion.setUserId(loginUser.getId());
                        return questionBankQuestion;
                    }).collect((Collectors.toList()));
            //使用事务去处理
            //注意：使用this去调用事务是不会生效的，spring事务基于代理实现，需要spring的代理对象
//            this.BatchAddQuestionsToQuestionBankInner(questionBankQuestions);
            //使用代理对象去调用事务
            QuestionBankQuestionService questionBankQuestionService  =(QuestionBankQuestionServiceImpl) AopContext.currentProxy();

            //异步处理每批数据，将任务添加到任务列表中
            CompletableFuture<Void> future = CompletableFuture.runAsync(() -> {
                questionBankQuestionService.BatchAddQuestionsToQuestionBankInner(questionBankQuestions);
            }, customExecutor).exceptionally(e -> {
                //捕获异常，如果某个任务出现异常，其他任务可能在执行，就会产生不确定的影响
                log.error("批量添加题目到题库失败", e);
                return null;
            });
            futures.add(future);

            //等待所有任务完成
            CompletableFuture.allOf(futures.toArray(new CompletableFuture[0])).join();

            //关闭线程池，释放资源
            customExecutor.shutdown();

        }

    }
    /**
     * 批量添加题目到题库(事务)仅供内部调用
     */
    @Override
    @Transactional(rollbackFor = Exception.class)
    public void BatchAddQuestionsToQuestionBankInner(List<QuestionBankQuestion> questionBankQuestions){
        for (QuestionBankQuestion questionBankQuestion : questionBankQuestions) {
            Long questionBankId = questionBankQuestion.getQuestionBankId();
            Long questionId = questionBankQuestion.getQuestionId();
            try {
                boolean result = this.save(questionBankQuestion);
                if (!result) {
                    throw new BusinessException(ErrorCode.OPERATION_ERROR, "向题库添加题目失败");
                }
            } catch (DataIntegrityViolationException e) {
                log.error("数据库唯一键冲突或违反其他完整性约束，题目 id: {}, 题库 id: {}, 错误信息: {}",
                        questionId, questionBankId, e.getMessage());
                throw new BusinessException(ErrorCode.OPERATION_ERROR, "题目已存在于该题库，无法重复添加");
            } catch (DataAccessException e) {
                log.error("数据库连接问题、事务问题等导致操作失败，题目 id: {}, 题库 id: {}, 错误信息: {}",
                        questionId, questionBankId, e.getMessage());
                throw new BusinessException(ErrorCode.OPERATION_ERROR, "数据库操作失败");
            } catch (Exception e) {
                // 捕获其他异常，做通用处理
                log.error("添加题目到题库时发生未知错误，题目 id: {}, 题库 id: {}, 错误信息: {}",
                        questionId, questionBankId, e.getMessage());
                throw new BusinessException(ErrorCode.OPERATION_ERROR, "向题库添加题目失败");
            }

        }

    }

    /**
     * 批量移除题目到题库
     * @param questionIdList
     * @param questionBankId
     */
    @Override
    public void BatchRemoveQuestionsFromQuestionBank(List<Long> questionIdList, long questionBankId){
        //数据校验
        ThrowUtils.throwIf(CollUtil.isEmpty(questionIdList), ErrorCode.PARAMS_ERROR, "题目id列表不能为空");
        ThrowUtils.throwIf(questionBankId <= 0, ErrorCode.PARAMS_ERROR, "题库id不能为空");
        //批量添加题目到题库
        for (long questionId : questionIdList) {
            LambdaQueryWrapper<QuestionBankQuestion> lambdaQueryWrapper = Wrappers.lambdaQuery(QuestionBankQuestion.class)
                    .eq(QuestionBankQuestion::getQuestionId, questionId)
                    .eq(QuestionBankQuestion::getQuestionBankId, questionBankId);
            boolean result = this.remove(lambdaQueryWrapper);
            ThrowUtils.throwIf(!result, ErrorCode.SYSTEM_ERROR, "从题库移除题目失败");
        }
    }

}
